Modal analysis of an infrared lightguide with a three-lobed core cross-section under the weak guidance approximation

This paper gives in brief the theoretical and computational investigation o f a new infrared lightguide having a three-lobed core cross-section. This s tructure is here introduced for the first time and may be conceived as a di stortion of a triangular core cross-section. Using the scalar wave approxim ation, the modal characteristic equation for the lowest order mode (v = 0) has been analytically derived. From this equation the modal dispersion curv es are obtained at two operating wavelengths lambda(0) = 1.55 mu m and lamb da(0) = 1.30 mu m.